The purpose of the Homeland Security Advisory System is to identify the level of threat by terrorists and inform the American people and Federal, State, and local authorities on the risk of attack so that appropriate action can be taken by each.

The following are the definitions of each level of alert according to the Whitehouse www.whitehouse.gov/news/releases/2002/03/20020312-1.html website:

Low risk of terrorist attacks. The following Protective Measures may be applied:

• Refining and exercising preplanned Protective Measures
• Ensuring personnel receive training on HSAS, departmental, or agency-specific Protective Measures; and
• Regularly assessing facilities for vulnerabilities and taking measures to reduce them.

General risk of terrorist attack. In addition to the previously outlined Protective Measures, the following may be applied:

• Checking communications with designated emergency response or command locations;
• Reviewing and updating emergency response procedures; and
• Providing the public with necessary information.

Significant risk of terrorist attacks. In addition to the previously outlined Protective Measures, the following may be applied:

• Increasing surveillance of critical locations;
• Coordinating emergency plans with nearby jurisdictions;
• Assessing further refinement of Protective Measures within the context of the current threat information; and
• Implementing, as appropriate, contingency and emergency response plans.

High risk of terrorist attacks. In addition to the previously outlined Protective Measures, the following may be applied:

• Coordinating necessary security efforts with armed forces or law enforcement agencies;
• Taking additional precaution at public events;
• Preparing to work at an alternate site or with a dispersed workforce; and Restricting access to essential personnel only.

Severe risk of terrorist attacks. In addition to the previously outlined Protective Measures, the following may be applied:

• Assigning emergency response personnel and pre-positioning specially trained teams; Monitoring, redirecting or constraining transportation systems;
• Closing public and government facilities; and
• Increasing or redirecting personnel to address critical emergency needs.